Miniature incandescent lamp and apparatus and method for making the same

ABSTRACT

Microminiature incandescent lamp having a tubular envelope with a glass central section and metal end sections heat-sealed to the central section. The envelope contains a filament coil secured to the end sections by mechanical cold-weld pinch-offs that seal the previously evacuated envelope. Envelopes are formed seriatim by feeding the components to an assembly station where the end sections are partially inserted into the central section. The resulting assemblies are conveyed to a sealing station where heat is directed only to the metal end regions of the envelope, so that only the end regions of the glass section are deformed in sealing. Filaments are formed and inserted into the envelopes by pulling a length of filament wire through a tubular guide, inserting an envelope over the guide, winding a filament coil from the end of the filament wire projecting from the guide, and then pulling the envelope over the finished filament. The outer diameter of the filament coil is initially greater than the inner diameter of the end sections of the envelope, so that the coil is stretched in length and reduced in diameter when it is drawn into the envelope.

United States Patent Belknap Oct. 2, 1973 [75] inventor:D0naldJ.Belknap,Takoma Park,

[731 Assignee: Nelson 11. Shapiro, Rockville, Md.;

Milton M. Field, Alexandria, Va.;

a part interest to each [22] Filed: May 4, 1971 211 Appl. No.: 140,260

Related US. Application Data [62 Division of Ser. No. 760,852, Sept. 19,1968, Pat. No.

[52] US. Cl 313/315,?113/318, 313/333,

. 313/344 [51] Int. Cl. H0lk 1/16, HOlj 5/50 [58] Field of Search313/318, 315, 331

[56] References Cited UNITED STATES PATENTS 3,320,466 5/1967 Ayres et a1313/318 2,886,629 5/1959 Van Geel..... 313/318 3,505,556 4/1970 Belknap313/318 3,431,540 3/1969 Kopelman et a1... 313/318 3,515,931 6/1970Takakuwa 313/318 Primary ExaminerRudolph V. Rolinec AssistantExaminerWm. H. Punter Attorney-Shapiro & Shapiro [57] ABSTRACTMicrominiature incandescent lamp having a tubular envelope with a glasscentral section and metal end sections heat-sealed to the centralsection. The envelope contains a filament coil secured to the endsections by mechanical cold-weld pinch-offs that seal the previouslyevacuated envelope. Envelopes are formed seriatim by feeding thecomponents to an assembly station where the end sections are partiallyinserted into the central section. The resulting assemblies are conveyedto a sealing station where heat is directed only to the metal endregions of the envelope, so that only the end regions of the glasssection are deformed in sealing. Filaments are formed and inserted intothe envelopes by pulling a length of filament wire through a tubularguide, inserting an envelope over the guide, winding a filament coilfrom the end of the filament wire project ing from the guide, and thenpulling the envelope over the finished filament. The outer diameter ofthe filament coil is initially greater than the inner diameter of theend sections of the envelope, so that the coil is stretched in lengthand reduced in diameter when it is drawn into the envelope.

3 Claims, 16 Drawing Figures Patented Oct. 2, 1973 I 6 Sheets-Sheet 1Patented 0a. 2, 1913 3,763,390

6 Sheets-Sheet 2 FIG. 2'

Patented Oct. 2, 1913 6 Sheets-Sheet :5

Fla. 4

Patented Oct. 2, 1973 3,763,390

6 Sheets-Sheet 4 FIG. 9

Patented Oct. 2, 1973 6 Sheets-Sheet 5 FIG. 11

FIG. 12

Patented Oct. 2, 1973 3,763,390

6 Sheets-Sheet 6 MINIATURE INCANDESCENT LAMP AND APPARATUS AND METHODFOR MAKING THE SAME This application is a division of Ser. No. 760,852,filed Sept. 19, 1968 for Miniature Incandescent Lamp and Apparatus andMethod for Making the Same now u.S. Pat. No. 3,578,429.

BACKGROUND OF THE INVENTION This invention relates to miniatureincandescent lamps and the like, especially microminiature lamps havingaxial geometry, and to methods and apparatus for making such devices.

The microminiature incandescent lamps described in the applicants priorU.S. Pat. Nos. 3,040,204; 3,193,906; and 3,226,218, meet the need forvery small, low-current indicator lamps which are compatible in sizewith todays microminiature electronic circuitry. Although axial lamps ofthis type are now being manufactured, they are relatively expensivebecause of the need for hand labor and specialized techniques. Jiggingis necessary in order to position properly and align the parts duringassembly. Heat-sealing the lamps within a vacuum environment, such asthat produced in a bell jar, is inconvenient and results in somewhatreduced efficiency and shortened lifetime because of the trapping withinthe lamp envelope of gases liberated by the molten glass of the envelopeat the time of sealing.

Other types of small incandescent lamps currently being manufactured donot require painstaking jigging and the inconvenience of bell jarsealing and are consequently less expensive. However, these lamps of amore conventional design usually have both leads projecting from thesame end of the lamp and employ a glass tubulation for evacuating theenvelope. This single-ended construction, as well as the need forprotecting the tipped-off end of the glass tubulation with a metal capor potting material, makes even the smallest of these lamps very muchlarger than the axial lamps of the applicants above-mentioned priorpatents. In addition the conventional lamps suffer from reduction inefficiency and lifetime brought about by the evolution of gas during thefinal tip-off of the glass tubulation.

The applicant's copending application Ser. No. 563,844, filed July 8,1966, now U.S. Pat. No. 3,505,556 for Miniature Incandescent Lamps andthe Like and Methods of Making the Same, describes an improvedincandescent lamp and methods of manufacturing the same. Some of theimportant distinctions of this lamp with respect to prior lamps are thatthe envelope is formed from a thin-wall glass sleeve central section,the ends of which are heat-sealed to metal terminal sleeves partiallyinserted therein axially, there being no deformation of the majorportion of the glass sleeve intermediate the ends. A filament isinserted into the envelope axially and its ends are engaged by the metalterminal sleves, which are pinched off in cold-welding operations toseal the envelope. It is to improvements in this highly advantageouslamp and the methods and apparatus for making the same that the presentapplication is directed.

BRIEF DESCRIPTION OF THE INVENTION It is accordingly a principal objectof the present invention to provide improvements in the lampconstruction and the methods of making the same described in the saidcopending application, and furthermore, to provide apparatus forfacilitating the mass production of such lamps and the like.

More specifically, it is an object of the invention to provide lampconstructions and methods and apparatus for making the same which permitthe manufacture of miniature lamps at lower cost, in greater quantities,and with fewer rejects than heretofore possible.

A further object of the invention is to provide a microminiature lampwhich ensures reliable contact between the ends of the filament and theterminals of the lamp.

Another object of the invention is to provide improved apparatus andmethods for manufacturing lamp envelopes and the like.

A further object of the invention is to provide improved apparatus andmethods for winding filament coils and the like and for inserting thesame into envelopes.

Briefly stated by way of example, the invention is concerned with amicrominiature incandescent lamp of axial geometry and having athin-wall tubular envelope with a light-transmissive intermediatesection and opposite conductive end sections sealed to the intermediatesection prior to assembly of the envelope with a filament. The envelopesare formed seriatim by feeding the components to an assembly stationwhere a pair of end sections is partially inserted into an intermediatesection. The thus-formed assembly is conveyed to a sealing station whereheat is applied locally to the conductive end sections to seal the endsections to the in termediate section. The envelope is then supportedupon a tubular guide through which a length of filament wire is drawn,and the end of the filament wire is engaged with a filament winder forforming the filament coil. After formation of the coil the envelope isdrawn over the coil in an operation which stretches the coil and ensuresgood electric contact with the end sections of the envelope. The endsections are pinched off by cold-welding operations which securelyanchor the corresponding extremities of the filament coil. Prior tocomplete sealing of the envelope by the pinch-off, the envelope isevacuated.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects,advantages, and features of the invention and the manner in which thesame are accomplished will become more readily apparent uponconsideration of the following detailed description of the inventiontaken in conjunction with the accompanying drawings, which illustratepreferred and exemplary embodiments, and wherein:

FIG. 1 is a longitudinal sectional view of a lamp of the invention shownin perspective an illustrating the relationship of the intermediate andend sections of the envelope with a filament coil and the retention ofthe filament coil and sealing of the envelope by mechanical pinch-offs;

FIG. 2 is a front elevation view of apparatus for forming lampenvelopes;

FIG. 3 is a horizontal sectional view taken along line 3-3 of FIG. 2 andillustrating the mechanism for holding the envelope components,inserting the end sections partially into the intermediate section, andadvancing the envelope assemblies;

FIG. 4 is a vertical sectional view taken along line 4-4 of FIG. 2 andillustrating the mechanism for advancing the lamp assemblies and themanner in which lamp assemblies are conveyed to a sealing station andthen to a pick-off station;

FIG. 5 is an enlarged vertical sectional view illustrating a detail ofthe lamp assembly conveyor;

FIG. 6 is a diagrammatic perspective view illustrating the manner inwhich end sections are inserted into the central section of the lampenvelope and showing the implements for advancing the lamp assembliesfrom the assembly stationa and holding back successive lamp envelopecomponents;

FIG. 7 is an enlarged vertical sectional view illustrating details ofthe manner in which the envelope end sections are supported and moved atthe assembly station;

FIG. 8 is a fragmentary front elevation view showing the manner in whichlamp assemblies are carried upon the conveyor;

FIG. 9 is a diagrammatic plan view illustrating the manner in which heatis applied to the envelope assembly at the sealing station;

FIG. 10 is a diagrammatic side elevation view illustrating the operationof the pick-off for removing lamp assemblies from the conveyor;

FIG. 11 is a side elevation view illustrating apparatus for formingfilament coils and inserting the same into envelopes in accordance withthe invention;

FIG. 12 is a plan view of the apparatus of FIG. 11;

FIG. 13 is an enlarged fragmentary vertical sectional view illustratingthe manner in which a lamp envelope is supported during the formation ofits filament;

FIG. 14 is an enlarged side elevation view illustrating details of theapparatus for forming the filament coil;

FIG. 15 is an enlarged plan view illustrating further details of theapparatus for forming a filament; and

FIG. 16 is a vertical sectional view illustrating the manner in which afilament is inserted into its envelope.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings,,andinitially to FIG. 1 thereof, an incandescent lamp constructed inaccordance with the invention comprises two basic parts: an envelope 10and a filament 12. The envelope has a main, intermediate or centralsection 14, preferably of thin-wall glass or ceramic tubing of circularcrosssection, and a pair of end sections 16 and 18, preferably of metaltubing of circular cross-section. For example, the glass section may beformed of 7052 or lead glass, while the metal sections may be formed ofAlloy 52, Kovar or platinum. The metal sections extend from oppositeends of the glass section in alignment and are hermetically sealed tothe ends of the glass tubing by glass-to-metal seals, as will bedescribed more fully hereinafter. A typical envelope for amicrominiature incandescent lamp may have a central section 0.06 inchlong with 0.0225 inch OD. and 6 mil wall thickness and end sections16,18 0.025 inch long with 0.0145 inch OD. and 0.005 inch ID. Thefilament 12 may comprise sixteen turns of 0.00025 inch Tungsten wirewound on a 0.004 inch diameter mandrel, for example. As will bedescribed more fully hereinafter, the

or gas-tight) seal. The pinch-off is formed by a coldwelding operation,that is, by the application of pressure without additional heat. Softmetals, such as fully annealed aluminum, 0.070 inch O.D. X0.010 wallKovar, annealed nickel, thin-wall 52 alloy and platinum are typicalmaterials which can be pinched-off in this manner. Suitable tools forthis operation are manufactured by CHA Industries, 1215 Chrysler Drive,Menlo Park, Cal. The lamp is evacuated through the open end section 18,which is then pinched off in the same manner as end section 16, to gripthe extremity 22 of the filament and to form another hermetic seal. Thecompleted lamp can be placed in a spring clip socket to hold the lampand provide end connections, or leads can be soldered to the metal ends.

The lamp envelopes may be manufactured as illustrated in FIGS. 2-10.Referring to FIG. 2, the envelope forming machine comprises a frameincluding a base 24 and a pair of spaced uprights 26 and 28. Supportedupon the frame above the base is a magazine 30 having three chutes 32,34, and 36. Adjacent to their tops chutes 32 and 34 are substantiallyparallel, but as they progress downwardly these chutes converge towardopposite sides of chute 36. The tops of the chutes are open to receivethe envelope components, chutes 32 and 34 receiving lengths of metaltubing (e.g., 0.375 inch long) and chute 36 receiving lengths of glasstubing, all of which are stacked vertically. The components may bepre-loaded into auxiliary magazines placed on top of magazine 30. Thewidths and depths of the chutes are chosen to provide sufficient freedomfor serial vertical movement of the envelope components without jamming.While unassisted gravity feed may be employed to advance the componentsalong the chutes, movement may be facilitated by adding weights to thetop of each stack of components to act as followers.

A table 38 is mounted on the frame at the assembly station locatedslightly below the bottom of the chutes. As shown in FIG. 3 the tablehas a pair of end portions 40 and 42 and a central portion 44 providedwith aligned notches 46A, 46B, 46A-48B, and 50. Notch 46A-46B is locateddirectly below the bottom exit of chute 32, notch 48A-48B directly belowthe bottom exit of chute 34, and notch 50 directly below the bottom exitof chute 36. The metal end sleeves of the envelope bridge the gaps 52and 54, and the glass tubing sections are centrally aligned by notch 50.The lowermost envelope component in each chute thus is received in thecorresponding notch. The tubular envelope components rest in theirrespective notches as indicated in FIG. 7, wherein one of the metalsleeves is shown supported in its receiving notch. The notches may berectangular in cross-section and somewhat narrower than the associatedtubular components so that the sleeves project from the notches asshown.

At the appropriate moment metal sleeves supported upon notches 46A-46Band 48A-48B are partially inserted axially into the glass sleevesupported upon notch 50. This operation is performed by pusher pins 56and 58 which reciprocate upon the table 38 in guide bores axially of theenvelope components. The pusher pins are normally held retracted byreturn springs 60 and 62 and are moved toward each other by cam followerarms 64 and 66 see FIG. 2 pivoted at 68 and 70 upon the frame and drivenby cams 72 and 74 fixed to a rotary shaft 76 journaled upon the uprights26 and 28. Weights 78 and 80 fixed to the upper ends of the cam followerarms urge the follower arms against the inclined end surfaces of the camdiscs 72 and 74. Alternatively, bias springs may be employed for thispurpose. The flattened sleeve-engaging ends of the pusher pins 56 and58, the height of which is less than that of metal sleeves 16 nd 18, areshown in FIG. 6 urging the metal sleeves into the glass sleeve 14 about0.010 inch.

The envelope assembly formed by the partial insertion of the metalsleevesinto the glass sleeve is now to be conveyed to a sealing station.To advance the envelope assembly from the assembly station initially,further pusher pins are provided. These are shown in FIG. 3 at 82, 84,86, and 88. The pins are fixed to a block 90 and reciprocate in unisonin guide bores upon the table 38. Pins 84 and 86 are joined by a pusherplate 92 slightly behind their forward ends.

Block 90 is normally held retracted by return springs 94 and 96 and iscam-driven to engage the pusher pins with the envelope assembly. Thedrive mechanism is shown in FIG. 4 and comprises an arm 98 pivotallysuspended at 100 from the frame and having an angulated forearm 102above the shaft 76 and provided with a cam follower block 104 fixed toits tip. The cam follower block is engaged by the curved circumferentialramp I06 of a cam disc I08 fixed to shaft 76. The cam has a notch 1110into which the point 112 of the follower block 1104 enters to disengagethe follower from the cam after the block has been driven by the ramp106 to cause the pins 82, 84, 86, and 88 and the plate 92 to engage thelamp assembly and move it out of the supporting notches, beneath theslighty elevated lower edge of the front plate of magazine 30, and ontothe ledge at the front of the table 38 as shown in phantom lines in FIG.6. A groove 50 is provided in the table portion 44 to accommodate theglass sleeve 14 as the assembly is moved forward. Only the lowermostcomponents are advanced, the. succeeding components resting on thepusher elements 82, 84, 86, 88, and 92 and being held back by the frontcover of the magazine 30. When the cam follower block 104 drops into thenotch 110 of cam 108, arm 98 is retracted by return spring 114 (FIG. 4),and block 90 is retracted by return springs 94 and 96 (FIG. 3)surrounding guide pins 94 and 96' to retract the pusher pins 82, 84, 86,and 88 and pusher plate 92 and to permit the next envelope components ofthe stacks to fall into the associated notches of the table 38. Thedrive connection between block 90 and arm 98 may include a pin 116 urgedto the left in FIG. 4 by a compression spring 118 of sufficient strengthto overcome the resistance of springs 94 and 96, but which iscompressible in the event of jamming during advancement of lamp envelopeassemblies.

After the pusher pins 56 and 58 have moved to insert a pair of metalsleeves partially into a glass sleeve and have retracted, and after thethus-formed envelope assembly is initially advanced by the pusher pins82, 84, 86, and 88 and plate 92, a conveyor picks up the envelopeassembly. In the form shown the conveyor comprises an arm I fixed to theshaft 76. The ends of the arm are bifurcated to form fingers 122 and 124'(spaced, e.g., 0.300 inch, and 0.175 inch wide) which pass through thegaps 52 and 54 of the table 38 and engage the metal sleeves 16 and 18 asshown in FIG. 8. Each finger has a shoulder 126 (FIG. 5) which engagesthe associated metal sleeve almost centrally thereof so as to sweep theenvelope assembly from the table 38. In order to retain the lampassembly upon the conveyor as the conveyor turns downwardly, a smallmagnet 128 is recessed in each finger at the active end of arm (it beingassumed that only one end of arm 120 is active in the illustrativeexample, although both ends may be used actively if suitably contouredcams for actuating the pusher pins described above are provided). Themagnets are held in position by set screws 130 and attract the metal endsleeves of the envelope assembly. FIG. 4 illustrates the conveyor arm120 just as it is about to pick up a lamp assembly from the table 38.

Shaft 76, and hence the conveyor 120 and the earns 72, 74, and 108, isdriven by a pulley 132 FIG. 2 fixed to one end of the shaft. The pulleyis driven by a belt 134 in turn driven by a smaller pulley hidden inFIG. 2 by pulley 132 upon the shaft 136 of a small electric motor 138supported on the base 24. It is desired to arrest the movement of shaft76 when the conveyor reaches the sealing station to be described for atime sufficient to apply the desired amount of heat to seal the metalsleeves to the glass sleeve of the envelope. For this purpose amicroswitch is mounted upon the frame and has its actuator arm 140adjacent to the pulley 132 where it may be engaged byan abutment 142carried by the pulley. When the abutment contacts the actuator arm, themicroswitch is opened, deenergizing the electric motor and alsode-energizing a normally energized solenoid 144. The solenoid issupported upon the base 24 so that when the solenoid is tie-energized,its spring-loaded armature 146 is projected to a position adjacent topulley 132, where it may be engaged by an abutment I48 carried by thepulley. The operation is such that the microswitch is actuated byabutment 142 just before the conveyor arm 120 reaches the sealingstation, and the drive train coasts until abutment 148 engages armature146, stopping the movement of shaft 76 with the envelope assemblycarried by conveyor 120 precisely located adjacent to a heater 150 atthe sealing station.

The heater may be a length of copper tubing projecting horizontally froma base-supported standard 152 and closed at its salient end. Pipe 150 isconnected to a source of gas, such as a suitably regulated mixture ofpropane and oxygen, and has a pair of tiny holes 154 and 1156 FIG. 9 inits side wall facing the conveyor arm 120. Tiny jets of burning gas 158and 160 extend from the openings 154 and 156 when the gas is ignited(the gas may burn continuously during operation of the apparatus) toheat regions of the metal sleeves l6 and 18 remote from the glass sleeve14. The jets may be spaced apart .125 inch for a lamp of the dimensionsgiven above, so that the heat for sealing the metal sleeves to the glasssleeve must travel along the metal sleeves to reach the glass sleeve.The envelope assembly is maintained in the vicinity of the heater forjust sufficient time to cause the ends of the glass adjacent to themetal sleeves to seal upon the metal sleeves. Deformation of the glasstubing is thus rectricted to the regions immediately at the seals. Withmicrominiature envelopes the glass section is so light weight that theglass section aligns itself axially with the metal sections, due to theadhesion of the melted glass, despite the fact that the glass section issuspended from the somewhat smaller diameter metal sections.

The dwell of the envelope assembly at the heater station is controlledby a conventional time-delay relay,

the delay-time control knob of which is indicated at 162 in FIG. 2. Thisrelay is actuated conventionally by the same microswitch which controlsthe motor 138 and the solenoid 144 and commences a delay period when themicroswitch de-energizes the motor and the solenoid. At the end of thedelay period the motor and the solenoid are rc-energized by the relay,and conveyor arm 120 rotates again, conveying the envelope to a pick-offstation.

The pick-off is in the form of three sheet metal fingers 164,166, and168 which project horizontally from a standard 170 on the base 24. Theend of the conveyor arm 120 sweeps under the pick-off, fingers 122 and124 of the arm passing through the spaces between fingers 164,166, and168 of the pick-off, so that the envelope is swept from the conveyor bythe pick-off fingers and drops as shown in FIG. to a suitable receptacle(not shown). The finished envelopes may be cleansed of any oxidationformed during the heating by an acid etching agent, such as concentratedhydrochloric acid, and then may be washed and dried.

The next principal step in the manufacture of a lamp in accordance withthe invention is the forming and insertion of the lamp filament. FIGS.11-16 illustrate these operations.

As shown in FIGS. 11 and 12, a spool S of filament wire W, such as thetype previously described, is rotatably supported upon a base 172 bymeans of spaced uprights 174 and 176 provided with pivots 178 and 180for the spool. One end of the very fine filament wire is extended fromthe spool to a table 182 mounted upon the base 172. Here the wire passesthrough an opening in a guide 184 and through an opening in a body ofresiliently compressible material 186, such as rubber, which may bevariably compressed by means of a screw-driven plate 188 to create anadjustable drag for setting the tension in the filament wire. The wirethen passes through an axial opening in a block 190. Block 190 see FIG.13 has a recess which receives and supports a guide sleeve 192 intowhich an envelope 10 of the invention may be inserted. The envelope isinserted over a stainless steel tube 194 held in the central bore of theblock 190 and long enough to project from an envelope fully insertedinto sleeve 192. The filament wire is pulled through the stainless steelsleeve 194 before the envelope is slipped into sleeve 192, so that theinsertion of the envelope causes the free end 196 of the filament wireto bend laterally as shown.

The free end 196 of the filament wire is grasped and pulled to thefilament winder 198 FIGS. 11 and 12 supported on a block 200 adjacent tothe table 182. The filament wire passes over a fine mandrel 204 whichprojects transversely to the wire from its support upon the armature ofa solenoid 206. The winding head comprising the solenoid is supportedupon the block 200 for rotation about the axis of the mandrel 204 and isdriven by a belt 208 from a drive pulley not shown Slip ring connectionsnot shown are used to supply the solenoid with current. The frame of thesolenoid carries a jaw 210, and the reciprocating armature of thesolenoid carries a jaw 212. Both jaws and the mandrel are rotatable withthe solenoid, the mandrel being fixed to jaw 212. Jaw 210 carries acantilevered wire guide 214 FIG. 14 which is bent to provide a pair ofV- shaped guide elements 216, 218, elements 216 and 218 being located asshown in FIGS. 14 and so that the filament wire may be drawn over themandrel, through guide element 216, through guide element 218 and thenbetween the mating portions 210A and 212A of the jaws 210 and 212. FIG.15 shows the guide 214 rotated counter-clockwise from the position ofFIG. 14.

When the solenoid 206 is energized, mandrel 204 is retracted into itsguide sleeve 220 upon jaw 210 and the jaws are separated. The filamentwire is threaded through the guide elements 216 and 218 and placedbetween the jaws. Then the solenoid is de-energized, so that thearmature return spring not shown drivesjaw face 212A against jaw face210A to grip the free end of the filament wire and to extend the mandrelunder the wire. If the armature of the solenoid is then turned about theaxis of the mandrel, the filament coil will be wound upon the mandrel asshown at 12 in FIG. 15. When a desired number of turns has been wound,the solenoid is energized to withdraw the mandrel, and the filament wireis cut as indicated at 222 in FIG. 15, so that the coil hangs from thewire attached to the supply spool.

The outer diameter of the filament coil is made slightly larger than theinner diameter of the metal end sections of the envelope, for example0.006 inch CD. as compared to 0.005 inch ID. for the metal end sections.If now the envelope which has been resting upon block is withdrawn fromsleeve 192 and pulled over the filament coil, the coil will have tostretch longitudinally, so as to increase the spacing of the turns andreduce their outer diameter, in order for the filament coil to enter theenvelope. This is illustrated in FIG. 16. The envelope is advanced overthe filament coil until the coil is entirely contained within theenvelope and until filament turns at the opposite ends of the coil arelocated within the respective end sections of the envelope. The portiOnof the filament coil attached to the spool may then be severed torelease the filament for retention in the envelope. The envelopes maynow be evacuated and sealed.

Suitable evacuating and sealing apparatuses and methods have beendescribed in the aforesaid copending application and are not per se thepresent invention. As set forth in that application, a plurality ofenvelopefilament units may be evacuated and sealed together. The lampsmay be mounted upright upon an apertured block by inserting themend-wise into the block apertutes, so that one metal end section of eachlamp is received in an aperture of the block. The block may contain alayer of compressible material which grips and seals about the exteriorof the inserted metal end sections, and the block apertures may beplaced over the nipples of the evacuation system. The upper metalsleeves of the supported lamps may then be pinched off at a regionintermediate the ends of the sleeves by the curved jaws of a mechanicalpinch-off tool of the type described previously. The jaws of the toolcome together upon the metal tubing, flattening the tubing where engagedby the jaws and pinching the tubing until it is severed into two axiallyseparated pieces. The piece sealed to the glass section of the envelopebecomes the metal terminal at one end of the lamp. The mechanicalpinch-off operation hermetically seals the metal sleeve without theaddition of heat, thereby avoiding the generation of gas and avoidingoxidation of the metal. The end of the filament coil becomes clamped inthe pinch-off, securely fixing the filament coil to the terminal sleeveof the envelope.

After the pinching off of one end sleeve, the lamps are evacuatedthrough the opposite end sleeve inserted in the supporting block. Heatmay be applied during the evacuation to bake out the lamps if desired.Also, the filaments may be flashed to de-gas them prior to final sealingof the lamps. Finally, the lower terminal sleeves are pinched off in themanner just described, so that both ends of the filament coil aresecurely gripped and the lamp is completely sealed.

By virtue of the invention lamp envelopes and filaments may be formedand assembled and the lamps completed expeditiously in large quantitiesby mass production techniques. The finished lamp has the potential oflonger life than prior art lamps because of the avoidance of thegeneration of gas during the final sealing of the lamps. The substantialelectrical and mechanical contact of the end turns of the filament coilwith the terminal sleeves of the lamp ensures good mechanical support aswell as excellent electrical continuity, thereby avoiding intermittentcontact problems.

While preferred embodiments of the invention have been shown anddescribed, it will be apparent to those.

skilled in the art that changes can be made in these embodiments withoutdeparting from the principles and spirit of the invention, the scope ofwhich is defined in the appended claims. For example, envelope supportsmay be provided upon block 200 to facilitate placement of the envelopeupon stainless steel tube 194.

The invention claimed is:

1. An incandescent lamp or the like comprising a tubular envelope havingan insulating central section and a pair of conductive terminal sectionsextending oppositely from said central section, and a wire coil havingturns extending into and engaging said terminal sections, said terminalsections having pinched ends beyond said central section, said pinchedends gripping said coil and sealing said envelope.

2. An incandescent lamp in accordance with claim 1, wherein said centralsection is a thin wall cylindrical glass tube heat-sealed to saidterminal sections.

3. An incandescent lamp in accordance with claim 1, wherein saidterminal sections are thin wall cylindrical metal tubes and said pinchedends are cold welds.

1. An incandescent lamp or the like comprising a tubular envelope havingan insulating central section and a pair of conductive terminal sectionsextending oppositely from said central section, and a wire coil havingturns extending into and engaging said terminal sections, said terminalsections having pinched ends beyond said central section, said pinchedends gripping said coil and sealing said envelope.
 2. An incandescentlamp in accordance with claim 1, wherein said central section is a thinwall cylindrical glass tube heat-sealed to said terminal sections.
 3. Anincandescent lamp in accordance with claim 1, wherein said terminalsections are thin wall cylindrical metal tubes and said pinched ends arecold welds.